Uptake and Effects of the Cypermethrin-Containing Sea Lice Treatment Excis super(R) in the Marine Mussel, Mytilus edulis

Cypermethrin is licensed for use on fish farms to control sea lice infestations in Scottish sea lochs. The uptake of cypermethrin by mussels which coexist with salmon farms was studied, and effects of the pyrethroid on mussels were also gauged by analysis of neutral red retention time of lysosomes, aerial survival, and shell closure. Isomeric ratios of cis:trans cypermethrin measured in mussels were 80:20, substantially higher than the ratio to which they were exposed. This trend is likely due to preferential metabolism of trans-isomers. A strong behavioral effect of shell closure was observed on exposure to 1000 mu g/l, but neutral red retention time and aerial survival were not affected by this dose.